Turbocharger: Testing and Inspection

Turbocharger and charge pressure regulating valve, checking
Safety notes

Note the points if test equipment has to be used during a road test:

WARNING:
^ Test equipment must always be secured on the rear seat and operated from there by a second person.
^ If test equipment is operated from the front passenger seat, the occupant could be injured by the passenger's airbag in an accident.

Special tools, testers and auxiliary items
^ Turbocharger tester V.A.G 1397 A
^ V.A.G 1551 Scan Tool or V.A.G 1552 with cable V.A.G 1551/3

Requirements for test:
^ Diagnostic Trouble Code (DTC) memory has been checked
^ Output DTM has been performed
^ Engine oil temperature at least 60 C
^ All vacuum connections airtight





- Loosen bolts -arrows- and remove engine cover panel -B-.





- Connect T-piece with measuring hose of turbocharger tester V.A.G 1397 A to fuel pressure regulator-arrow-.
- Route measuring hose under rear edge of bonnet and into passenger compartment via right-hand window.





- Switch on turbocharger tester and set measuring range selector switch to position -1- (absolute pressure).
- Connect measuring hose to connection -1-.

Notes:
^ Hose connections must be completely airtight, otherwise measurements will not be correct.
^ Ensure that measuring hose is not pinched at bonnet or side window.
^ Pressing memory key M on turbocharger tester will store the last measured value until memory key M is pressed again or tester is switched off.
^ The decimal point in the display flashes to indicate that the value being stored.
^ If the battery voltage of the turbocharger tester drops below the minimum level, an arrow will appear at the top left of the display.
^ Before performing the test, drive the vehicle at a brisk speed for at least 3 km (without stops).
^ A second mechanic is required to note the readings on the tester when the vehicle is moving.
^ Observe safety notes.

- Accelerate vehicle from 2000 RPM at wide open throttle in fourth gear, and watch rev counter.





- Press memory key -M- on turbocharger tester at 3000 RPM.
^ Specification: 1.550 ... 1.650 bar

Note: If no charge pressure is obtained and a throbbing noise can be heard in the engine compartment, the causes can be as follows:
^ Air recirculation valve malfunctioning.
^ Vacuum line to air recirculation valve leaking or has become disconnected.